[erlang-questions] Sets, ordsets, gb_sets, sofs. What is going on?

Richard O'Keefe <>
Sun Mar 28 07:38:54 CEST 2010

On Mar 27, 2010, at 5:48 AM, Robert Virding wrote:
> The discussion about using or not using '=:=' operator for comparison
> is an unfortunate by-product of Erlang not having a complete set of
> pure term comparison operators which do not convert integers. With
> 20-20 hindsight it would have been much better to have a set of proper
> term comparison operators and a separate set of numerical comparison
> operators which only work on numbers. Then there would be no
> difference.

Given Erlang's Prolog ancestry, and the fact that Prolog _had_ two
complete sets of operators, I really can't take "hindsight" as the
appropriate term.  It's also particularly unfortunate that Erlang
switch the meaning of Prolog's == (exact identity) and =:= (numeric
identity) operators.

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